Internal Freeform technology uses advanced software to create a lens that is customized not just to your prescription but that is also digitally calculated to match the movements of your eye. This allows for natural eye movements through the lens - rather than awkward head movements to find the visual center of the lens. And Internal Freeform lenses go one step further by accounting for how far the frames will sit from your eyes, the tilt that results when resting on your nose, and even the curvature around your face. True personalized vision!